Apparatus for the checking of a diesel engine



APPARATUS FOR THE CHECKING OF A-DIESEL ENGINE Filed Sept. 29, 1964 Dec.19, 1967 G. H- A. FOURTANE 2 She ets-Sheet 1 IVE,

INVENTOE. GERARD HEN/Z! AUGUST/N FOURTA 9 G. H. A. FOURTANE 3,358,499

APPARATUS FOR THE CHECKING OF A DIESEL ENGINE Filed Sept. 29, 1964 2Sheets-Sheet 2 ATTORNEYS.

United States Patent 3,358,499 APPARATUS FOR THE CHECKING OF A DIESELENGINE Grard Henri Augustin Fourtan, Asnieres, Se ne, France,

assignor to Societe dEtude et de Fabrication de Material Electronique(SEFME) S.A.R.L.

Filed Sept. 29, 1964, Ser. No. 399,971 4 Claims. (Cl. 73--119) Theproblem of the complete checking of diesel engines during operation hasnot yet been met with any fully satisfactory solution.

-In fact, the rational checking of a diesel engine must necessarilycomprise:

(a) the checking of the injection and of the injectors,

(b) the checking of the initial advance (timing of the pump), and of thecurve of the automatic advance (if it occurs),

(0) the checking of the engine operation (control of the overspeedcut-off, control of the idling).

With the previously known devices, these different verifications aremade independently.

It is already known to check the calibration of the injectors by makingup the injectors and trying them out on the test bench.

It is known to check a pump for a diesel engine by using a test injectoror false injector in order to test, by stroboscopic means, the timingand the operational rhythm of the pump.

It has on the other hand Ibeen proposed to transform the energy of thefuel projected by the pump at each injection into an electric signalwhich, when suitably used, gives indications on the operation of thepump (speed of rotation for example).

There does not exist any apparatus which permits testing duringoperation of the different elements of a diesel engine without havingrecourse in one manner or another to a standard reference element; theinjectors are tested on the bench with the aid of a control machine,which one can consider as a reference pump or compressor. The pumps ontheir part are tested with the aid of a test injector.

The present invention relates to a method and apparatus for the checkingof a diesel engine during operation, without the use of a referenceelement.

According to this method, and with the aid of this apparatus, one checkssuccessively the injection, and more particularly the opening times ofthe various injectors, the injection pump being that of the engine,then, the injectors being tested and adjusted, the operation of thepump, and more particularly its initial advance and its advance curve,the pump normally supplying the engine injectors, finally the operationof the engine and more particularly the operation of cut-off and idling.

Thus, the different elements of the engine are checked in their actualworking conditions and not in isolation.

The invention relates equally to an assembly for the measure andchecking of a diesel engine during operation, comprising essentially anadjustable transducer device capable of being connected into the inletof each injector and to the outlet of the pump, this device transformingthe variations in pressure at the points under consideration into anelectric signal which is periodically interrupted and of which theduration (of emission or nonemission) and the frequency are'equallycharacteristic; a measuring box making use of this duration andfrequency, the duration of the signal corresponding to an indication oftime open, the frequency corresponding to a tachometric indication; astroboscopic lamp which flashes at the frequency of the signal, or at amultiple of this Patented Dec. 19, 1967 2 frequency; phase adjustingmeans enabling the phase of the flashes of the lamp to be adjusted inrelation to the signal, this phase adjustment appearing on the measuringbox in the form of an indication of advance.

The following description and the accompanying drawings, which are givenabove all by Way of non-limiting examples, will make better understoodthe manner in which the invention can be put into effect.

In the accompanying drawings FIGS. 1, 2 and 3 represent respectively anelevation and two transverse sections at of the transducer according tothe invention;

FIG. 4 represents diagrammatically the assembly according to theinvention;

FIG. 5 represents the front face and FIG. 6 represents the stroboscopicdevice which is used.

A transducer deviceof the single-contact type which is mounted at theinlet of the injectors or at the outlet of the pump of a diesel andtransducer the pressure variations at its positions into a periodicsignal is already known. Such device comprises essentially a chamber inwhich the fuel emerging from the pump or about to enter the injectorarrives, the chamber, at the opposite end to the arrival of the fuelbeing closed by a piston provided with a helical return spring, thedisplacements of the spring causing the opening (or closing) of anelectric circuit, from which the production of a pulsed sig nal enablesthe frequency to be theoretically obtained.

However, such a device presents serious drawbacks:

(a) In practice, the use of a helical spring results in parasiticvibrations rendering the apparatus imprecise;

(b) An empirical adjustment of the tension of the springs envisageduntil the appearance of the required electrical pulsations. It wassupposed that, as a result of this empirical adjustment, the beginning(or the end) of an electric pulsation corresponded to the beginning (orthe end) of an injection;

(c) In fact, even in the best conditions, it was found that thisapparatus was unusable, except for the use of the periods of the signalwhich it created, which could be translated for example into anindication of the speed; the apparatus was completely useless for themeasurement of injection time, the start of movement of the piston didnot correspond necessarily to a determining instant of the injection.

The transducer according to the invention avoids these drawbacks.

More precisely, the transducer according to the invention for thetransformation of variations of pressure at the inlet of the injectorsor at the outlet of the pump of a diesel engine comprises essentially acylindrical connecting head, capable of being mounted, with the aid ofappropriate fittings, in the stream of the relevant connecting pipe, acylinder, extending transversely of the connecting head,'a cylindricaladjusting head placed at the end of the cylinder opposite to theconnecting head and on the axis of the latter, a piston movable in thecylinder between the connecting head and the measuring head, thismovement corresponding to the opening or the closing of a circuit, thusgiving rise to an electric signal, the end of the piston correspondingto the connecting head being pushed back by the pressure obtaining inthe connecting head, the end of the piston corresponding to themeasuring head being applied against a leaf spring mounted in themeasuring head, the tension of the leaf spring being adjustable by meansof an adjustment ring threaded on the outside of the measuring chamberand pressing against the ends of the leaf spring, this ring carryingdirectly a graduation corresponding to different calibrations of theinjectors, such that the electric signal of the measuring box;

produces, when the connecting head is mounted on. a conduit leading intoan injector, corresponding in duration (of emission or of non emission)to the time during which the pressure in the conduit is greater than theset calibration pressure, that is to say for, an injector adjusted tothis calibration pressure, at the time of injection. j Thus, one can notonly use thefrequency of the signal thus produced (to measure forexample the nu mb er of injections per unit of time), but also itsduration.

FIGS. 1, land 3 represent the new transducer according to the invention(FIG. 3 being a section on the line IIIIII of FIG. 1 and FIG. 2 asection on the line II-II of PG. 3.)

The device according to the invention comprises an annular conectinghead 1, a cylinder 2 connecting with the connecting head, a measuringhead 3 mountedjat the other end of the cylinder 2, these threeelfement sforming part of a single body. The head 1 may, with the aid ofappropriate fittings be mounted in series on a diesel engine, eitherupstream of the injectors or at the outlet of the injection pump, withits axis coinciding with the axis of the conduit or tube on which it ismounted.

In the interior of the cylinder 2 is slidably mounted a piston 4carrying a sliding sealing joint 4a. The pressure in the interior of theconnecting head 1 acts on the fact 4b of the piston 4. At its other end,the piston 4 carries a bearing head 4c. This bearing head 40 is incontact with an assembly of leaf springs 5. These leaf springs havetheir ends 5a located in a channel 3a in the annular head 3.

They are held in place by an adjusting ring 6, which is threaded ontothe chamber 3. This ring 6 carries a scale 6a;which is movable inrelation to an index 3a of the measuring head 3. This scale 3a indicatesthe adjustment of the tension of the springs 5 corresponding to thevalues of the calibrations of the injectors to be controlled. As long asthe pressure in the head 1 is lower than the value correspondingtheoretically to the opening of the injectors calibrated to theindicated value, the head 40 of the piston 4 remains in contact with ametal abutment 7 which is insulated by a plate 8. To this metal abutment7 is connected two contacts or conducting connecting sockets 9. As longas the head 4c is in contact with 7, the latter is at the potential ofthe assembly 1, 2, =3 (to earth). As soon as the piston 4 begins tomove, all "electric contact between the piston 4 and the abutment 7 isbroken. An electric circuit connected at 9 and having earth return by9-7-4c4-3-2-1 is open as soon as 4c leaves the abutment 7. Thus anelectric circuit can be set up in which a signal is created whichcorresponds to the value of the pressure in 1, in relation toa value ofthe set calibration. The duration of this signal, more precisely withthe indication of the length separating two successive electricimpulses, corresponds very exactly to the time of opening of an injectorcalibrated to the set value. Of course, with another electric system, itis the true duration of the electric impulses which would be the usefulvalue.

Advantageously, the cylinder 2 is bored with an opening 2a to get rid ofany fuel which may have seeped past the ring 4a.

Preferably also, the adjusting ring 6 can be locked by a lock ring 18,screwed like it on the head 3, but with a different thread pitch.

Whatever its nature, the transducer delivers a signal which for theduration, as well as the frequency, is significant.

The signal is made use of in the following manner: The transducer Taccording to the invention is used in conjunction with a measuring .box11 (of which the front face is shown in FIG. 5) and a stroboscopic flash12, to carry out the complete control and adjustment of a diesel engineindicated by M.

The measuring box is supplied by a DC. source S, which 4 advantageouslyis the vehicle battery (thus the earthin of the measuring box is itselfassured at the same time as its supply) which is driven by the engine M.The box is moreover connected by a cable 13 to the transducer T (for theestablishment of the detectioncircuie), and by a cable, 14- to thestroboscopic lamplZ, This lamp comprises a. button 12a which must bepushed to start 7 its operation and a control button 121) forcontrolling the phase difference between the; transducer signal and thelight signal emitted by the lamp 12.

The front face of the measuring box 5) comprises the following elements:

(a) At the top left an indicator dial showing the amount of advance andof injection on two scales. The first (greater scale) is graduated; inengine degrees (040 The second (smaller scale) inpump degrees (O-20).Between these two scales is the'injection scale.

b Bottom left a switch knob STOP-PUMP TIMING- PUMPADVANCE-INJECTION-which selects the operations whichjas will be"Seemtake place in a given interval.

(c) Top right the tachometer with two scales, of two sensitivities. i

The first (upper scale) 0 s 1000 s a. 0 to 5000 rpm.

indicates the engine speed The second (lower scale) 0 to 500 r.p.m. 0 to2500 rpm.

and the frequency of operation of the stroboscopic lamp The assemblyaccording to "the invention is inade V of in the following manner:

(1) Preparation for the checks In order, it is convenient to idehtifythevehicle so as to know from the makers specifications:

the setting of the injectors the timing of the pump in degrees inrelation to TDQ the curve of advance if the pump is provided with auto.-

:matic advance.

If the engine does not carry the marking TDC either on the flywheel oron the crankshaft pulley, it is convenient first of all to determine thelatter with the greatest precision by dropping a valve according to thecustomary method. The flywheel is then marked with a fixed referencemark. i

(2) Measurements (A) Checking the injectz'0n.The graduation of thetransducer T being adjusted according to the setting given by theconstructor, a series of measurements of injection time is made byconnecting successively the transducer upstream successively of each ofthe injectors of the engine.

On the scale injection of the left-hand dial, readings.

are taken which, if the injectors are suitably adjusted, shouldcorrespond to the predetermined values. For example, in a four-cylinderengine readings are taken on moving the pick-up from the 4th to the 3rdthen to the 2nd and to the 1st injection circuit as follows:

cylinder 4: 1.5 cylinder 3: 1 1.5 cylinder 2: 2.2

cylinder 1:

cylinder 4: 1.5 cylinder 3: 1.0 cylinder 2: 1.5

cylinder 1: 1.5

Before removing injector No. 3 on which the setting is probably too low,the tachometer is adjusted to the range 2500/ 500 and theengine isprogressively accelerated. If the tachometer follows the increase inengine speed in a normal manner, the injector setting is definitely toolow. On the other hand if during the course of the acceleration a suddenbreak occurs (return of the needles of the two dials to zero), theengine continuing to accelerate, it is a question of a fault in thesealing-tightness of the pump cylinder. The latter should therefore beremoved.

In the opposite case, the injector being removed and adjusted orreplaced, new readings are taken on the same circuit. If the lowestreading is still obtained, the pump is to be suspected. If in the courseof an injection test the needles of the measuring apparatus moveerratically, this indicates intermittentent sticking of the injector. Ifthe needles remain at zero, the injector has stuck in the open position.

(B) Checking the initial advance.The injection control being finished,the pick-up is mounted on the first injection circuit at the outlet ofthe pump (or the last circuit).

(a) If the flywheel or the crankshaft pulley comprises a mark injectioninstant, the control switch (bottom left on the front face of thecontrol box) is set to PUM'P TIMING. The stroboscopic lamp is pointed atthe flywheel or the pulley, and the control button pressed with theengine running at idling speed: the mark injection instant should thenbe opposite the fixed index, the pump timing being then correct. Shouldthis not occur, the pump timing is retarded if the movable mark is inadvance of the fixed mark and the pump timing is advanced if the movingindex mark has passed the fixed mark, until coincidence of the two marksis obtained.

(b) The flywheel r crankshaft pulley carrying the mark T DC.In thiscase, the initial advance determined by the maker is known. Theoperating switch is adjusted to AD- VANCE. With the aid of the knurledphase adjustment knob 12b situated on the stroboscopic lamp 12, thepredetermined number of degrees of advance is set on the scale engineadvance; the stroboscopic lamp is pointed at the flywheel or the pulley,the button 12a is pressed, with the engine idling: the mark TDC shouldthen coincide with the fixed mark if the pump is correctly timed. Shouldthis not occur, the reading on the scale engine advance is read byadjusting with the aid of the knurled knob the phase ditference betweenthe two marks when coincident. This permits the mistiming to be measuredand indicates to the operator the correction to be applied according tothe same method as described in the preceding paragraph.

(C) Checking the automatic advance curve.--When the injection pump isprovided with an automatic advance device, the control of the differentvalues of this curve specified by the maker is carried out by repeatingthe operation described above under different operating conditions andnoting the angular values and the engine operating conditions for eachof them.

In the case of an automatic advance device which has stuck, the lattermay occur at the lower part or in the middle or at the upper part of therange of the curve. In the case of an advance device which sticks in themiddle of the range, one first of all checks the operation of theinitial timing control for an exaggerated initial advance; onaccelerating up to the cut-off condition, this advance would remainfixed.

If the different top dead centres of an engine are known and if they aremarked on the flywheel or the crankshaft pulley, the injection advanceof each cylinder can be verified and by deduction the cam angles of thepump can be measured. In the case of a pump having adjustable push rods,it would be easy to correct these angles should this be necessary.

(D) Verification of the cut-ofi 0perati0n.This verification is carriedout with the aid of the tachometer using the scale 2500/5000. Thisverification is very important: operation at a speed lower than thatspecified by the maker results in poor performance. On the other hand,operation at a higher speed reduces the life of the engine.

(E) Idling adjustment.-This is also effected with the aid of thetachometer using the scale 500/ 1000, reference being made to the makersspecifications.

Thus, the apparatus according to the invention permits complete andrational checking of all the elements of a diesel engine. This iseffectively obtained by the use of a transducer giving a signal whichhas a real significance both in respect of its duration and itsfrequency. This being so, the invention is of course not limited to theembodiments described but extends to all the variants conforming to thespirit of the invention.

What is claimed is:

1. A device for sensing duration of injection of a fuel injection systemparticularly a diesel engine fuel system having injectors comprising atubular member having a first end with means for connecting this end toa fuel line to be measured and for establishing communication of theinterior of said tubular member with the fuel line, said tubular memberhaving a second opposite end with a head portion, an electrical contactdisposed adjacent the juncture of said tubular memher and said headportion, a piston having a first end subjected to the fuel pressure insaid fuel line and being movable in said tubular member in response to apredetermined pressure in said fuel line, said piston having a bearinghead adjacent its opposite end engage able with said contact and beingmovable away from said contact only upon the occurrence of apredetermined pressure in the fuel line, spring means biasing the pistonto maintain the head portion in engagement with said contact, adjustablesetting means carried by said tubular member acting on said spring meansto maintain its biasing force on said piston to an amount preventing themovement of said piston head portion away from and out of contact withsaid electrical contact except upon the attainment in the fuel line andsaid tubular member of a predetermined setting pressure comparable tothe theoretical opening pressure of the injector associated with thefuel line, and electrical sensing means connected to said contact forsensing when said piston member is engaged and when it is disengagedfrom said contact, said spring means comprising a spring beam, means insaid head portion for holding each end of said spring beam adjacent saidpiston head portion, said adjustable setting means including anadjusting member carried by said head portion and being movable inrespect thereto against said spring beam adjacent each end thereof forvarying the biasing pressure of said spring means against said pistonand thus the pressure of the fuel at which the piston will move.

2. A device according to claim 1, wherein said adjusting membercomprises a ring threaded onto said head portion, and a locking ring forlocking said adjusting ring in an adjusted position.

3. A device according to claim 2, wherein said adjusting ring includes ascale defined around the periphery thereof, said head portion having anindex disposed for orientation with said scale.

4. A device according-to claim 1, wherein said sensing means includes ameasuring box having means for indicating when the theoretical pressureis exceeded, and a stroboscope lamp connected to said measuring box forchecking the readings in accordance with the indicated rotational speedof the engine and the injector.

References Cited UNITED STATES PATENTS OTHER REFERENCES Obert, E. F.:Internal Combustion Engines, second edition, Scranton, Pa.,International Textbook Co., 1959, pp.

129 through 132 and 381. Copy in Group 285.

RICHARD C. QUEISSER, Primary Examiner.

JAMES GILL, Examiner.

JERRY W. MYRACLE, Assistant Examiner.

1. A DEVICE FOR SENSING DURATION OF INJECTION OF A FUEL INJECTION SYSTEMPARTICULARLY A DIESEL ENGINE FUEL SYSTEM HAVING INJECTORS COMPRISING ATUBULAR MEMBER HAVING A FIRST END WITH MEANS FOR CONNECTING THIS END TOA FUEL LINE TO BE MEASURED AND FOR ESTABLISHING COMMUNICATION OF THEINTERIOR OF SAID TUBULAR MEMBER WITH THE FUEL LINE, SAID TUBULAR MEMBERHAVING A SECOND OPPOSITE END WITH A HEAD PORTION, AND ELECTRICAL CONTACTDISPOSED ADJACENT THE JUNCTURE OF SAID TUBULAR MEMBER AND SAID HEADPORTION, A PISTON HAVING A FIRST END SUBJECTED TO THE FUEL PRESSURE INSAID FUEL LINE AND BEING MOVABLE IN SAID TUBULAR MEMBER IN RESPONSIVE TOA PREDETERMINED PRESSURE IN SAID FUEL LINE, SAID PISTON HAVING A BEARINGHEAD ADJACENT ITS OPPOSITE END ENGAGEABLE WITH SAID CONTACT AND BEINGMOVABLE AWAY FROM SAID CONTACT ONLY UPON THE OCCURRENCE OF APREDETERMINED PRESSURE IN THE FUEL LINE, SPRING MEANS BIASING THE PISTONTO MAINTAIN THE HEAD PORTION IN ENGAGEMENT WITH SAID CONTACT, ADJUSTABLESETTING MEANS CARRIED BY SAID TUBULAR MEMBER ACTING ON SAID SPRING MEANSTO MAINTAIN ITS BIASING FORCE ON SAID PISTON TO AN AMOUNT PREVENTING THEMOVEMENT OF SAID PISTON HEAD PORTION